428 
J ournal of Agricultural Research 
Vol. XXX, No. 5 
Table V. — Green weights of cowpeas from pots receiving various quantities of dicy' 
anodiamide with and without sodium nitrate 
NORFOLK SANDY LOAM 
Source of nitrogen 
Fertilizer 
ratio 
NH3-P2O5-K2O 
Green 
weight 
No nitrogen_, 0-8-4 
Sodium nitrate 40__ 4-8-4 
Sodium nitrate 40, dicyanodiamide 5... 4.5-8-4 
Sodium nitrate 40, dicyanodiamide 10_| 5-8-4 
Sodium nitrate 40, dicyanodiamide 20_ i 6-8-4 
Sodium nitrate 40, dicyanodiamide 40_ j 8-8-4 
j 
Sodium nitrate 40, dicyanodiamide 80_ 12-8-4 
Dicyanodiamide 5_ j . 5-8-4 
Dicyanodiamide 10_ j 1-8-4 
Dicyanodiamide 20_ j 2-8-4 
Dicyanodiamide 40_! 4-8-4 
Dicyanodiamide 80_-_j 8-8-4 
Grams. 
32.6 
35.5 
33.9 
35.5 
24.9 
25.1 
17.1 
19.7 
17.2 
25.9 
20.9 
25.8 
20.3 
16.6 
4.3 
9.9 
27.4 
27.9 
33.3 
26.3 
23.9 
29.8 
24.1 
15.7 
1.4 
3.8 
CHESTER LOAM 
No nitrogen_ 
Sodium nitrate 40_ 
Sodium nitrate 40, dicyanodiamide 5_. 
Sodium nitrate 40, dicyanodiamide 10. 
Sodium nitrate 40, dicyanodiamide 20. 
Sodium nitrate 40, dicyanodiamide 40- 
Sodium nitrate 40, dicyanodiamide 80. 
Dicyanodiamide 5_ 
Dicyanodiamide 10_ 
Dicyanodiamide 20_ 
Dicyanodiamide 40_ 
Dicyanodiamide 80_ 
0-8-4 
4- 8-4 
4.5-8-4 
5- 8-4 
6- 8-4 
8-8-4 
12-8-4 
.5-8-4 
1- 8-4 
2- 8—4 
4-8-4 
8-8-4 
Average 
Variation 
from 
check 
} 34.1 
} 34.7 
0.6 
| 25.0 
-9.1 
| 18.4 
-15.7 
| 21.6 
\ 
-12.5 
i 20.9 
-13.2 
} 7 ' 1 
-27.0 
J- 27.7 
-6.4 
} 29.8 
-4.3 
} 2-. 9 
-7.2 ■ 
}■ 19.9 
-14.2 
} 2.6 
-31.5 ■ 
Nodule 
formation 
Abundant. 
Do. 
’ Do. 
Do. 
/Many. 
\Abundant. 
/Many. 
\Abundant. 
/Many. 
\ Do. 
Do. 
Do. 
Do. 
Do. 
/None. 
\Many. 
/ Do. 
\ Do. 
/Abundant. 
\Many. 
/ 50.6 
\ 52.4 
} 51.5 
/ 58.6 
\ 61.6 
} 60.1 
8.6 { 
/ 56.4 
\ 53.6 
V 55.0 
3.5 { 
J 54.7 
\ 48.1 
| 51.4 
-M 
/ 57.3 
\ 52.3 
} 54.8 
3.3 | 
f 57.7 
] 
[ 
J 53.8 
1 53.7 
| 55.3 
3.8 | 
l 56.1 
1 
l 
f 51.9 
\ 45.3 
\ 48.6 
- 2.9 { 
/ 51.6 
\ 54.1 
i 52.9 
w 
/ 54.1 
l 49.7 
}• 51.9 
• 4 { 
/ 47.1 
\ 52.8 
| 50.0 
-!.5 { 
/ 42.9 
l 49.0 
| 46.0 
-5.5 { 
/ 37.5 
\ 43.0 
} 40.3 
-11.2 { 
Do. 
Do. 
ew. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
The difference between the extent 
of the injury of dicyanodiamide on 
wheat and cowpeas suggests an explana¬ 
tion for some of the widely varying 
results reported in the literature. For 
one crop the material may be very 
toxic, even in small amounts, while for 
other plants it is nearly inert or indi¬ 
rectly toxic because of its prevention 
of nitrification. This emphasizes the 
desirability of further work with other 
crops. However, dicyanodiamide was 
somewhat toxic even for the more resis¬ 
tant crop, wheat, and for this reason 
the material should not be present in 
appreciable quantities in fertilizers. 
